1. Field of the Invention
The present invention relates to a bobbin including a bobbin thread end housing mechanism that is capable of storing a bobbin thread without crushing the shape of the bobbin thread and that is also capable of satisfactorily storing the bobbin thread while preventing the end of the bobbin thread wound around a bobbin winder spindle from coming loose and complicated handling.
2. Description of the Related Art
In general, a bobbin is used in sewing by a sewing machine for home use. In general, during sewing machine use, usually, to use a needle thread and a bobbin thread of the same color, a user of the sewing machine stores, for each of thread colors, a plurality of bobbins wound with frequently-used threads and replaces the thread together with the bobbin to match the thread color of the needle thread.
However, the thread wound around the bobbin easily comes loose because of vibration and rotation and gets entangled with other threads to make work complicated. Moreover, for example, the entangled thread is cut and discarded to be wasted. As techniques for preventing the thread from coming loose, there are techniques disclosed in Japanese Patent Application Laid-Open No. 2010-12016, Japanese Patent Application Laid-Open No. 2007-185432, Japanese Utility Model Registration No. 3072607, and the like.
First, in Japanese Patent Application Laid-Open No. 2010-12016, a bobbin main body includes a thread stopper ring, which is a spring-like elastic member adjusted to the width of a thread winding section of a bobbin. A thread wound around the bobbin is retained by the thread stopper ring to prevent the thread from coming loose. In Japanese Patent Application Laid-Open No. 2007-185432, a V-shaped cutout is provided on one side of a flange of a bobbin. The end of an excess thread is inserted into and locked in the cutout.
In Japanese Utility Model Registration No. 3072607, a commercially available thread spool is used rather than a bobbin for winding a bobbin thread. The thread spool has structure in which, in a flange on one side or on both sides, a lid member having the same diameter as the flange is fit by a convex section and a groove having a concentric shape to hold and retain a thread end between the flange and the lid member.
In Japanese Patent Application Laid-Open No. 2010-12016, the thread stopper ring is a member separate from the bobbin main body. The thread stopper ring has to be detached from the bobbin main body during sewing work. Therefore, workability is extremely low. Moreover, it is likely that the thread stopper ring is lost during the sewing work. In Japanese Patent Application Laid-Open No. 2007-185432, the V-shaped cutout is formed in the flange of the bobbin.
Therefore, in a horizontal shuttle sewing machine, if the cutout faces a needle thread passing side, the cutout comes into contact with the needle thread to cause a stitch performance failure and a thread cut. Therefore, the flange having the cutout has to be set on the opposite side of the needle thread passing side. However, if a winding direction of a thread is incorrect when the thread is attached to an inner shuttle, this also causes a stitch performance failure and a thread cut.
In such a method for retaining a thread in the past, a thread is retained while being held and crushed. It is not preferable for the thread to be retained in a state in which stress is applied to the thread.
In Japanese Utility Model Registration No. 3072607, since the commercially available thread spool is used, the thread spool cannot be directly applied to the configuration of a bobbin case. Therefore, the thread spool cannot be attached to the inner shuttle.